JPH076497Y2 - Oil sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an oil sensor for detecting a lubricating oil shortage state by the resistance of the lubricating oil itself.

[Problems to be solved by conventional techniques and devices] Generally, in a general-purpose engine, a vehicle engine, and the like, if the operating state is continued without noticing that the lubricating oil is insufficient, it causes damage such as seizure. Equipped with an oil sensor that constantly monitors the oil amount,
The engine is stopped or the warning light is turned on to prevent damage to the engine.

An example of this type of oil sensor is disclosed in Japanese Patent Laid-Open No. 62-934.
There is a reed switch using a reed switch as disclosed in Japanese Unexamined Patent Publication No. 17-62, JP-A-62-26379, or a hydraulic switch, but in an oil sensor using a reed switch, a reed switch is used. The structure such as a float, a magnet, etc. is complicated, and it must be assembled in the crankcase in advance, which is inconvenient to handle.

Further, an oil sensor for detecting oil pressure cannot be used in a splash-lubricated engine that is not equipped with an oil pump, which has a problem in versatility.

On the other hand, in other technical fields, a sensor for measuring fluid resistance and detecting a fluid shortage is known.

This so-called fluid sensor is composed of a rod-shaped inner electrode, and an outer electrode surrounding the inner electrode with a predetermined interval, and a resistance value between the two electrodes when immersed in a fluid,
The presence or absence of fluid is detected by comparing the resistance values between both electrodes in the non-immersed state.

However, when this type of fluid sensor is used as an oil sensor of an engine, since the inner electrode is rod-shaped, a large bending stress acts on the guide that points to the base of the inner electrode, and the load on this guide is large. There is a problem in vibration resistance.

Further, conventionally, an operator generally solders the inner electrode of the fluid sensor and the core wire of the shield wire to each other, resulting in poor work efficiency and non-mass production.

Further, the base portion of the inner electrode and the base portion of the outer electrode are fixed via an insulating member. However, when a fluid is attached to the surface of the insulating member to form a film, the fluid is insufficient. Nevertheless, since the fluid acts as a resistor to establish a conduction state between the electrodes, there is a disadvantage that the fluid shortage cannot be detected.

Generally, the viscosity of the fluid to be detected is almost constant, and since the fluid fluctuation is static, the fluid adhering to the above-mentioned insulating member is dropped by its own weight, so there is no problem in fluid detection, but driving The atmosphere in the crank chamber of the inside engine is filled with the splash lubricating oil, and the splash lubricating oil is always attached to the insulating member. In particular, when the engine temperature rises and the viscosity of the lubricating oil decreases, the lipophilicity of the insulating member increases and a lubricating oil film is easily formed,
There is a problem that the lack of lubricating oil cannot be detected in advance.

[Object of the Invention] The present invention has been made in view of the above circumstances. A first object of the present invention is to reduce the weight of the entire device and to improve vibration resistance.
An object is to provide an oil sensor that achieves high reliability of the product.

A second object of the present invention is to provide an oil sensor which can be mass-produced and whose cost can be reduced.

A third object of the present invention is to provide an oil sensor that can reliably detect a lack of lubricating oil even if the viscosity of the lubricating oil decreases.

[Means and Actions for Solving the Problems] (1) In the first oil sensor according to the present invention, the core wire of the shield wire is inserted and connected to the sensor inner electrode formed in a hollow shape, and the sensor inner electrode is connected to the outside of the sensor. It is loosely inserted into a sensor body that also serves as an electrode and has an open tip, and the base end side of the sensor inner electrode and the base end side of the sensor body are fixed via an insulating member, and the shield wire is further attached to the sensor body. Since the shielded wire is connected to the sensor inner electrode, the sensor inner electrode is hollow, so the weight is reduced, the load on the insulating member holding the sensor inner electrode is reduced, and the vibration resistance is improved.

(2) A second oil sensor according to the present invention is one in which a small hole for solder infiltration is formed at the tip of the electrode inside the sensor, and when assembled, the core wire of the shield wire is hollow in the electrode inside the sensor. When the tip of the in-sensor electrode is immersed in a solder bath after that, the solder permeates into the hollow portion through the solder infiltration small hole, and the core wire is soldered to the in-sensor electrode.

(3) In the third oil sensor according to the present invention, at least a portion of the insulating member exposed to the front end opening side of the sensor body is non-lipophilic, and the splash lubricating oil in the crankcase is It becomes difficult to adsorb to the insulating member, and formation of an oil film on the surface is prevented.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

The drawings show an embodiment of the present invention. Fig. 1 is a vertical sectional view of an oil sensor, Fig. 2 is a sectional view taken along line II-II of Fig. 1, and Fig. 3 shows a state in which the oil sensor is mounted on an oil pan. It is a fragmentary sectional view shown.

(Structure) Reference numeral A in the figure is an oil sensor, and the sensor body 1 of this oil sensor A is formed of a conductive member such as metal, and also serves as an outer sensor electrode.

A screw head 1a is formed on the head of the sensor body 1, a flange 1b is formed on the lower portion thereof, and a screw portion 1c is formed on the lower portion of the neck. Also, the sensor body 1
A hollow portion 1e penetrating from the head (base portion) side to the tip portion 1d is formed in the above, and an air vent hole 1f opening to the hollow portion 1e is formed in the middle of the sensor body 1. .

A step portion 1g is formed on the base side of the hollow portion 1e of the sensor body 1, and a step portion 2a of an in-sensor electrode guide 2 which is an example of an insulating member is hooked on the step portion 1g. The in-sensor electrode guide 2 is made of a high resistance insulating resin material having heat resistance.

In addition, a groove 2b is annularly provided in the lower part of the neck of the stepped portion 2a of the sensor inner electrode guide 2, and the groove 2b seals between the inner wall of the hollow portion 1e of the sensor body 1 and the groove 2b. The ring 3 is interposed. Furthermore, the tip of the in-sensor electrode guide 2 forms a tapered surface 2c that converges in the tip direction, and the diameter of the body portion between the tapered surface 2c of the in-sensor electrode guide 2 and the groove 2b is the above. Hollow part 1e of sensor body 1
The inner diameter is the same as or slightly smaller than the inner diameter.

In addition, the entire circumference of the electrode guide 2 in the sensor, or at least the portion exposed to the tip portion 1d side of the hollow portion 1e, that is, the tapered surface 2c and the tip surface thereof, is made of a heat-resistant material such as fluororesin A member having a hydrophilic property and a non-lipophilic property is coated.

Further, the base of the sensor inner electrode 4 made of a metal pipe or the like is fitted in the center of the sensor inner electrode guide 2.
The sensor internal electrode 4 is formed by casting integrally with the sensor internal electrode guide 2 and has a rib for preventing slipping off at the base thereof.
4a is installed in a circle. Further, a solder impregnation small hole 4c communicating with the hollow portion 4b is formed on the tip surface of the in-sensor electrode 4.

Further, the inner sheath 5a of the heat-resistant shield wire 5 inserted from the top surface side of the inner sensor electrode guide 2 is inserted into the hollow portion 4b of the inner sensor electrode 4, and the core wire 5b protruding from the tip of the inner sheath 5a. Is in contact with the bottom of the hollow portion 4b, and is connected and fixed to the bottom of the hollow portion 4b through solder that has permeated through a small hole 4c formed in the tip surface of the in-sensor electrode 4.

Further, the shield wire 5d exposed from the tip of the outer sheath 5c of the shield wire 5 is spread on the top surface of the in-sensor electrode guide 2, and the conductive washer 6 is brought into contact with the upper surface thereof. A conductive clip washer 7 is attached to the upper surface so that the outer periphery of the sensor clip 1 comes into contact with the inner wall of the hollow portion 1e of the sensor body 1 to prevent it from coming off. Is conducted through the section.

Further, a plug body 8 made of an insulating material such as epoxy resin is fitted and fixed on the upper surface of the clip washer 7,
The plug 8 is used to seal between the hollow portion 1e of the sensor body 1 and the outer sheath 5c of the shield wire 5.

On the other hand, a pin connector 9 connected to the control device 5 is connected to the other end of the shield wire 5, and the pin connector 9
The outer periphery of is covered with a waterproof cap 10.

Reference numeral 11 denotes an oil pan provided at the bottom of the crankcase of the engine, and a sensor mounting port 11a for screwing and fixing the oil sensor A through a packing 12 is formed on one side of the oil pan 11.

(Operation) Next, an embodiment of the present invention having the above-described configuration will be described.

(Assembly procedure) The plug body 8, the clip washer 7, and the washer 6 are sequentially inserted from the pin connector 9 side into the hollow portion 4b of the in-sensor electrode 4 integrally molded with the in-sensor electrode guide 2 in a predetermined manner. The inner sheath 5a exposed at the tip of the shield wire 5 that has been peeled off is inserted, and the core wire 5b protruding from the tip of this inner sheath 5a is brought into contact with the bottom surface of the hollow portion 4b.

Next, the tip end surface of the in-sensor electrode 4 is conveyed downward to the solder bath, and the tip end surface of the in-sensor electrode 4 is dipped in the solder bath. Then, this sensor internal electrode 4
The solder permeates into the hollow portion 4b through the small hole 4c formed in the tip surface of the core wire 5b, and the core wire 5b of the shield wire 5 is connected and fixed to the bottom portion of the hollow portion 4b through the solder.

After that, the O-ring 3 is attached to the groove 2b circularly provided in the sensor inner electrode guide 2, and then the sensor inner electrode 4 is inserted into the hollow portion 1e of the sensor body 1 from the screw head 1a side.

Then, the step portion 2a of the sensor inner electrode guide 2 integrated with the sensor inner electrode 4 is hooked on the step portion 1g formed in the hollow portion 1e of the sensor body 1, so that the sensor inner electrode guide 2 and the sensor inner electrode are formed. 4 is positioned on the sensor body 1. As a result, the O-ring 3 isolates (seals) the step portions 1g, 2a side from the tip portion 1d side of the sensor body 1.

Next, the washer 6, the clip washer 7, and the plug 8 inserted through the shield wire 5 are attached to the sensor body 1.
It is inserted into the hollow portion 1e of. Then, the clip washer 7 is pressed into the inner wall of the hollow portion 1e while being pressed, and the shield wire 5d of the shield wire 5 is pressed against the top surface of the sensor inner electrode guide 2 via the washer 6. As a result, the shield wire 5d and the sensor body 1 are electrically connected via the washer 6 and the clip washer 7.

On the other hand, the plug 8 is fitted to the head side of the hollow portion 1e,
The gap with the hollow portion 1e is sealed.

Then, the oil sensor A assembled as described above is inserted through the packing 12 into the sensor mounting opening 11a formed on one side of the oil pan 11 of the engine, and the threaded portion 1c of the sensor body 1 is inserted.
To fix it by screwing (state of FIG. 3). Further, the pin connector 9 is connected to the control device 15.

(Oil Detection Operation) When a key switch (not shown) is turned on and the engine is operated, a voltage is applied to the lubricant oil shortage determination means 15a of the control device 15 and the oil sensor starts detection of lubricant oil shortage.

When the lubricating oil is sufficiently stored in the oil pan 11, the sensor body 1 and the tip of the sensor inner electrode 4 are immersed in the lubricant oil, and the sensor body 1 and the sensor inner electrode 4 are separated from each other. The resistance of the lubricating oil is detected.

Since the resistance value of the lubricating oil is smaller than the space insulation resistance value between the sensor body 1 and the sensor inner electrode 4, the lack of lubricating oil is detected by the difference between the resistance values, and the control device 15
The lubricating oil shortage determination means 15a determines whether or not there is lubricating oil, that is, whether or not there is lubricating oil up to a specified level, based on the difference between the two resistance values.

Further, when the engine is driven, the sensor internal electrode 4 shakes due to the engine vibration, and a load is applied to the sensor internal electrode guide 2 that holds the base of the sensor internal electrode 4, but the sensor internal electrode 4 is hollow. Therefore, the burden is reduced and vibration resistance is good.

On the other hand, when the lubricating oil stored in the oil pan 11 is insufficient and the tip of the oil sensor is exposed from the lubricating oil surface, the space insulation resistance value is detected between the electrodes of the sensor body 1 and the sensor inner electrode 4. In the lubricating oil shortage determination means 15a of the control device 15, a warning is displayed on the lubricating oil shortage display means 15b, or the engine is stopped to inform the operator of the lack of lubricating oil, and seizure of the engine, etc. Prevent from happening.

Further, the lubricating oil is floating in the crankcase atmosphere while the engine is being driven, and the hollow portion 1e of the sensor body 1 is
However, since at least the tapered surface 2c and the tip end surface of the in-sensor electrode guide 2 are coated with a non-lipophilic member, even if it is a splashed lubricating oil with reduced viscosity at high temperature, The taper surface 2c and the tip surface are not adsorbed.

Therefore, despite the lack of lubricating oil, the inner wall of the hollow portion 1e and the inner electrode 4 of the sensor have the tapered surface 2
It is possible to reliably detect the insufficient lubricating oil state without causing electrical conduction through the c and the lubricating oil droplets attached to the tip surface.

The present invention is not limited to the above-mentioned embodiment, and for example, the in-sensor electrode guide 2 may be formed of a non-lipophilic member such as fluororesin. Also, the sensor body 1 may be formed of a conductive resin.

[Effects of the Invention] As described above, according to the present invention, the following effects are achieved.

(1) As described in claim 1, a sensor in which a core wire of a shield wire is inserted and connected to a sensor inner electrode formed in a hollow shape, and the sensor inner electrode also serves as a sensor outer electrode and has a tip opened. By loosely inserting into the body, fixing the base end side of the sensor internal electrode and the base end side of the sensor body via an insulating member, and further connecting the shield wire of the shield wire to the sensor body, the structure Is simplified, the weight of the entire device is reduced accordingly, and the sensor internal electrode is formed in a hollow shape, so that the load applied to the insulating member holding the sensor internal electrode can be reduced and the vibration resistance is improved. Not only can it be achieved, but high reliability of the product can be obtained.

(2) As described in claim 2, by forming a solder immersion small hole at the tip of the sensor internal electrode,
Since the solder can be soaked into the hollow portion from the small holes, the soldering can be performed in the automatic soldering tank, and accordingly, the mass productivity can be improved and the cost can be reduced.

(3) As described in claim 3, since at least a portion of the insulating member exposed to the front end opening side of the sensor body is non-lipophilic, the lubricating oil is adsorbed to this portion. It is possible to reliably detect the lack of lubricating oil.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a vertical sectional view of an oil sensor, Fig. 2 is a sectional view taken along line II-II of Fig. 1, and Fig. 3 shows a state in which the oil sensor is mounted on an oil pan. It is a fragmentary sectional view shown. 1 ... Sensor body, 1d ... tip part, 2 ... insulating member,
4 ... In-sensor electrode, 4c ... Small hole for solder immersion, 4b ...
Hollow part (of electrode in sensor), 5 ... Shield wire, 5b
…… Core wire, 5d …… Shield wire.

Claims (3)

[Scope of utility model registration request] 1. A core wire of a shield wire is inserted into and connected to a hollow sensor inner electrode, and the sensor inner electrode is loosely inserted in a sensor body which also serves as a sensor outer electrode and has an open tip. An oil sensor characterized in that a base end side of an electrode and a base end side of the sensor body are fixed via an insulating member, and a shield wire of the shield wire is connected to the sensor body. 2. The oil sensor according to claim 1, wherein a small hole for solder infiltration is formed at the tip of the electrode inside the sensor. 3. The oil sensor according to claim 1, wherein at least a portion of the insulating member exposed to the front end opening side of the sensor body is non-lipophilic.